If you have trouble with getting scratched up on your arms while hooking these take care of the issue! They also protect your rug as you work from becoming soiled from your arms and the front of your shirts from getting snagged. When your frame is not in use they keep you from getting scratched up when you brush against it. Your pattern goes on your frame then you place this over it. While they are made for our frames that are 17x15 they do fit other frames close to this size that are square, rectangular or octagon shaped frames.